1. Cross Reference to Related Application
The same inventors have filed a U.S. patent application entitled "Bromate as Inhibitor of Nitrosamine Formation for Nitrate Stabilized Isothiazolones and Process" [Ser. No. 07/785,586] on Oct. 30, 1991.
2. Field of the Invention
This invention relates to bromate stabilized compositions of 3-isothiazolones, their preparation, and their use in controlling living organisms.
3. Description of the Prior Art
3-Isothiazolones have generated high commercial interest as microbicides to prevent spoilage caused by microorganisms of a large number of aqueous and non-aqueous products subject to such spoilage. 3-Isothizolones are highly effective microbicides (as used herein, "microbicides" includes bactericides, fungicides and algaecides and microbicidal activity is intended to include both the elimination of and inhibition or prevention of growth of microbial organisms such as bacteria, fungi and algae); by suitable choice of functional groups, they are useful in a broad range of applications. However, it was early recognized that either in storage prior to addition to the matrix to be stabilized or after addition, their efficacy was decreased because the isothiazolone was not stable under practical conditions of long-term storage. Means have thus been sought from the beginning of research with such compounds to improve their stability.
U.S. Pat. Nos. 3,870,795 and 4,067,878 teach the stabilization of 3-isothiazolones against chemical decomposition by addition of a metal nitrite or metal nitrate, preferably a di- or trivalent metal ion nitrate. The use of said metal nitrates has become conventional in commericial 3-isothiazolone products. These patents also disclose that other common metal salts, including carbonates, sulfates, chlorates, perchlorates and chlorides are ineffective in stabilizing solutions of isothiazolones, such solutions usually being in water or in an hydroxylic solvent. Bromate salts are not taught nor considered in these patents.
Metal nitrates are known to cause problems in some 3-isothiazolone systems, the major problem being conversion of secondary or tertiarty amine impurities to nitrosamines under certain conditions. As a group, nitroso compounds are generally suspected to be possible carcinogens.
Alternatives have been developed to overcome the problems of metal nitrates; however, these alternatives introduce new problems. For example, it is known to use certain organic stabilizers for 3-isothiazolones, generally for use situations where metal salts may create problems, such as corrosion, coagulation of latices, insolubility in non-aqueous media, interaction with the substrate to be stabilized, and the like. Formaldehyde or formaldehyde-releasing chemicals are known as stabilizers, (see U.S. Pat. Nos. 4,165,318 and 4,129,448), as are certain organic chemicals such as orthoesters (U.S. Pat. No. 4,906,274) and epoxides (U.S. Appln. Ser. No. 194,234).
In certain applications, however, it is desirable to avoid addition of organic stabilizers by virtue of their volatility, decomposition in the presence of water or under high heat, higher cost, potential toxicity, and the like. Formaldehyde is a suspected carcinogen, and it is desirable not to use formaldehyde in applications where contact with human skin or lungs may occur.
It is known to use sodium bromate and potassium bromate in the baking industry as bread and flour improving agents (see Merck Index, 11th ed.).